The interconnection of individual electrical circuit components and printed wiring boards, for example, has until recently been accomplished by the well-known method of soldering the component leads to the board wiring. Although effective electrical connections were thus achieved, the soldering operations were time consuming and, further, created connections which were more or less permanent. Replacement of a defective component or the substitution of a component, for example, necessitated the unsoldering of the component leads thus adding to the cost of circuit maintenance and repair. This problem has been aggravated with the advent of large-scale integrated circuit packs having groups of many, closely spaced terminals. To meet the problem and obviate the necessity of soldering large number of terminals and at the same time permit the ready replacement of electrical components, socket connectors have been provided. Such connectors have contact receptacles in which component terminals may be inserted, the connector contacts then being permanently soldered to the circuit wiring board. Although the socket connectors offer the obvious advantage of plug-in connection of circuit packs or other components and thereby facilitate component replacement, the connectors in turn present other problems.
Insertion of the terminals of an electrical component in the receptacles of a socket connector is generally accomplished against spring action, which action must be sufficient to ensure positive electrical contact. When many terminals are involved, which is typically the case, considerable force may be required to insert the many terminals in the corresponding receptacles of the connector. Since the terminals are small and fragile, the insertion force required leaves the terminals vulnerable to bending, misalignment, and other damage to the contact surfaces. The risk of damage, of course, is present on each replacement occasion and the exercise of considerable care has been required to ensure proper seating of the electrical component terminals.
The foregoing insertion force problem has led to the development of so-called zero insertion force connectors. In these connectors, the electrical contact forces on the component terminals are not fully applied until the terminals are completely or nearly completely inserted in their receptacles. The terminals may thus be freely inserted in the connector receptacles without danger of damage. In a number of prior art zero insertion force arrangements such as that disclosed in U.S. Pat. No. 3,883,207 of T. K. Tomkiewicz issued May 13, 1975, for example, the socket connector is adapted to receive the terminals of a single integrated circuit pack such as a dual in-line pack. When a number of such circuit packs or modules are to be electrically interconnected with a circuit board, a corresponding number of individual socket connectors must also be provided as intermediate elements. This manifestly adds to the not inconsiderable cost of providing the zero insertion force mechanisms of the socket connectors themselves. It is accordingly an objective of the present invention to simplify the zero insertion force mechanism while at the same time making possible the employment of a single mechanism to simultaneous interconnect a plurality of electrical circuit modules with a printed wiring board.